Fluidic actuator

ABSTRACT

A fluidic actuator comprising a pair of high pressure pistons which operate in a push-push mode against an output bell crank. These pistons are actuated by a high pressure gas through a pair of upstream fixed orifices and a pair of downstream variable orifices or a pair of ball poppet valves operable by a poppet flapper. The flapper is displaced by a pair of low pressure pistons which are driven by a beam deflection fluidic amplifier.

United States Patent 1191 Dunaway Apr. 9, 1974 F LUIDIC ACTUATOR I [75] lnventor: J. C. Dunaway, Falkville, Ala.

[73] Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC.

[22] Filed: Sept. 9, 1972 [21] Appl. No.: 290,291

[52] US. Cl 91/3, 91/51, 91/186,

91/189 [51] Int. Cl. FlSb 13/02, FOlb 1/00 [58] Field 01 Search 91/51, 186, 189,3

[561 References Cited UNITED STATES PATENTS 12/1947 Bentley et a1 91/51 8/1949 Segerstad 91/51 3,020,885 2/1962 Weinstack et a1. 91/51 3,031,846 5/1962 Wiegand 91/51 3,557,660 1/1971 Palmer .1 91/51 Primary Examiner-Paul E. Maslousky Attorney, Agent, or Firm-Edward J. Kelly; Herbert Berl; Harold W. Hilton ABSTRACT A fluidic actuator comprising a pair of high pressure pistons which operate in a push-push mode against an 3 output bell crank. These pistons are actuated by a high pressure gas through a pair of upstream fixed orifices and a pair of downstream variable orifices or a pair of ball poppet valves operable by a poppet flapper. The flapper is displaced by a pair of low pressure pistons which are driven by a beam deflection fluidic amplifier.

4 Claims, 1 Drawing Figure 1 FLUIDIC ACTUATOR SUMMARY OF THE INVENTION I The actuator includes a pair of high pressure pistons mounted in a housing in side-by-side relationship. The pistons operate in a push-push mode against an output bell crank. A pair of low pressure pistons are mounted in the housing in coaxial relationship with the high pressure pistons and a flapper is disposed between the lower pressure pistons and the high pressure pistons. The flapper opens and closes a pair of ball poppet valves which are connected into the cylinders of the high pressure pistons. The ball poppets are operated in a push-push mode by the flapper. When one ball poppet is completely closed the other ball poppet is completely open. This creates a maximum pressure in the closed poppet side and a minimum pressure in the other side to provide a differential pressure across the high pressure pistons which generates a torque in the bell crank. The low pressure push-push pistons are driven by a beam deflection fluidic amplifier.

BRIEF DESCRIPTION OF THE DRAWING The FIGURE is an elevational sectional view of the fluidic actuator of the present invention.

DESCRIPTIONOF THE PREFERRED EMBODIMENT As shown in the FIGURE, fluidic actuator includes a housing 12 having upper and lower portions 1 1 and 13. Upper portion 11 of housing 12 encloses a pair of high pressure pistons 14 and 16 in a pair of cylinders and 17, respectively. Lower portion 13 houses a pair of low pressure pistons 18 and 20 in a pair of cylinders 19 and 21, respectively. A pair of ball poppet valves 22 and having balls 23 and 25 therein are respectively disposed in communication with the lower surfaces of pistons 14 and 16. A ball poppet flapper 26 is disposed in a chamber 27 between the upper surfaces of pistons 18 and 20 and the ball poppet valves. Flapper 26 is provided with hemispherical surfaces 28 and 30 at the ends thereof for releasable engagement with the upper surfaces of pistons 18 and 20, respectively. Flapper 26 is pivotally secured at 32. I

As shown in the FIGURE pistons 14 and 18 are in substantially coaxial relationship with poppet valve 22 and surface 28 of flapper 26 is also disposed intermediate and in alignment with pistons 14 and 18. A port 34 is disposed in communication with cylinder 15 and poppet valve 22 and a second port 36 is disposed in communication with cylinder 17 and poppet valve 25.

A high pressure inlet port 38 is in communication with ports 34 and 36 through a pair of horizontally extending ports 40 and 42, respectively. Ports 40 and 42 are each provided with restrictions 41 and 43 therein. The restrictions define fixed orifice means.

A bell crank 44 is pivotally secured in the upper end 45 of housing 12 at pivot 46 and is provided with surfaces 48 and 50 for engagement with the upper surfaces of pistons 14 and 16. I

To provide the low pressure for actuating pistons 18 Fluid amplifier 48 further includes an inlet nozzle 56 and 20 a fluid amplifier 48 is operatively connected to 6 the lower end 49 of housing 12. Fluid amplifier 48 is provided with a pair of outlets 52 and 54 respectively disposed in communication with cylinders 19 and 21.

and a pair of control ports 58 and 60.

In operation in the bistable mode the actuator is always in one extreme position. A high pressure gas is applied to supply port 38. A low pressure gas is applied to fluidic amplifier power nozzle 56. Assuming a control signal is applied to control port 60, then the gas from the amplifier is directed through output 52 of the amplifier into cylinder 19 to move piston 18 upwardly while piston 20 remains in the down position. Upward movement of piston 18 rotates flapper 26 clockwise. Engagement of the upper surface of piston 18 and surface 28 of the flapper, causes ball 23 to seat in poppet valve 22 and ball 25 to vent in poppet valve 24 making the pressure in cylinder 15 high and on piston 16 low creating a torque on bell crank 44 in the clockwise direction.

If the control signal is removed from control port 60. and applied to control port 58 the gas from the power nozzle will flow through outlet 54 and into cylinder 21 to move piston 20 upwardly while piston 14 is in the down position. Upward movement of piston 20 rotates flapper 26 counterclockwise. Engagement of the upper surface of piston 20 and surface 30 of flapper 26 causes ball 25 to seat in poppet valve 24 and ball 23 to vent in poppet valve 22, making the pressure in cylinder 17 high and on piston 14 low creating a torque on bell crank 44 in the counterclockwise direction.

It is to be understood that although the above description is directed to a bi-stable mode, a proportional mode may also be resorted to. Additionally, although pistons are referred to in the description as the low pressure force transmitting members, bellows and diaphragms may be resorted to.

I claim:

1. A fluidic actuator comprising:

a. a body enclosing a first pair of cylinders each haiving a piston therein, said cylinders disposed in communication with a source of high pressure;

b. a second pair of cylinders each having a piston therein, said second pair of cylinders disposed in communication with a source of low pressure;

0. a fluid amplifier having a pair of output ports respectively disposed in communication with each of said second pair of cylinders to provide said source of low pressure,

d. actuating means operatively connected to said second pair of pistons and disposed for venting one of said first pair of cylinders while retaining said high 7 pressure in the second one of said first pair of cylinders for creating pressure differentials across the first pair of pistons for selective displacement thereof, said actuating means including a ball poppet valve disposed in communication with each of said first pair of cylinders, and a flapper means operatively connected in each of said second pair of cylinders for opening or venting a predetermined one of said ball poppet valves; and,

e. output means disposed for engagement with said first pair of pistons for actuation responsive to displacement of said pistons.

2. A fluidic actuator as set forth in claim 1 wherein said housing includes upper and lower portions, said high pressure pistons being housed in said upper portion and said low pressure pistons being enclosed in said lower portion.

3. A fluidic actuator as set forth in claim 2 including high pressure inlet means disposed in said upper portion of said housing, said inlet means includes an inlet port, a first pair of ports disposed in communication with said first pair of cylinders and said poppet valves 5 P and a second pair of ports disposed in communication 

1. A fluidic actuator comprising: a. a body enclosing a first pair of cylinders each haiving a piston therein, said cylinders disposed in communication with a source of high pressure; b. a second pair of cylinders each having a piston therein, said second pair of cylinders disposed in communication with a source of low pressure; c. a fluid amplifier having a pair of output ports respectively disposed in communication with each of said second pair of cylinders to provide said source of low pressure, d. actuating means operatively connected to said second pair of pistons and disposed for venting one of said first pair of cylinders while retaining said high pressure in the second one of said first pair of cylinders for creating pressure differentials across the first pair of pistons for selective displacement thereof, said actuating means including a ball poppet valve disposed in communication with each of said first pair of cylinders, and a flapper means operatively connected in each of said second pair of cylinders for opening or venting a predetermined one of said ball poppet valves; and, e. output means disposed for engagement with said first pair of pistons for actuation responsive to displacement of said pistons.
 2. A fluidic actuator as set forth in claim 1 wherein said housing includes upper and lower portions, said high pressure pistons being housed in said upper portion and said low pressure pistons being enclosed in said lower portion.
 3. A fluidic actuator as set forth in claim 2 including high pressure inlet means disposed in said upper portion of said housing, said inlet means includes an inlet port, a first pair of ports disposed in communication with said first pair of cylinders and said poppet valves and a second pair of ports disposed in communication with said inlet and said first pair of ports.
 4. A fluidic amplifier as set forth in claim 3 including fixed orifice means disposed in said second pair of ports. 